Ezra 3:8

Now in the second year of their coming unto the house of God at Jerusalem, in the second month, began Zerubbabel the son of Shealtiel, and Jeshua the son of Jozadak, and the remnant of their brethren the priests and the Levites, and all they that were come out of the captivity unto Jerusalem; and appointed the Levites, from twenty years old and upward, to set forward the work of the house of the LORD.

Numbers 4:3

From thirty years old and upward even until fifty years old, all that enter into the host, to do the work in the tabernacle of the congregation.

1 Chronicles 23:4

Of which, twenty and four thousand were to set forward the work of the house of the LORD; and six thousand were officers and judges:

1 Chronicles 23:24-32

These were the sons of Levi after the house of their fathers; even the chief of the fathers, as they were counted by number of names by their polls, that did the work for the service of the house of the LORD, from the age of twenty years and upward.

Ezra 4:3

But Zerubbabel, and Jeshua, and the rest of the chief of the fathers of Israel, said unto them, Ye have nothing to do with us to build an house unto our God; but we ourselves together will build unto the LORD God of Israel, as king Cyrus the king of Persia hath commanded us.

Treasury of Scripture Knowledge

Summary

Now in the second year of their coming unto the house of God at Jerusalem, in the second month, began Zerubbabel the son of Shealtiel, and Jeshua the son of Jozadak, and the remnant of their brethren the priests and the Levites, and all they that were come out of the captivity unto Jerusalem; and appointed the Levites, from twenty years old and upward, to set forward the work of the house of the LORD.

Twenty years old

Bible References

Twenty years old

Numbers 4:3
From thirty years old and upward even until fifty years old, all that enter into the host, to do the work in the tabernacle of the congregation.
1 Chronicles 23:24
These were the sons of Levi after the house of their fathers; even the chief of the fathers, as they were counted by number of names by their polls, that did the work for the service of the house of the LORD, from the age of twenty years and upward.

King James Version Public Domain